Method of and apparatus for metal casting



l. R. I. cfAsE. l METHOD 0F AND AFRARATUSTQR METAL CASTING.

APPLICAT'IQN HLiDMAR. a. |921.A

' PatentedSeptlf-19 1922. 2 SHEETS-SHEET I.

R.T.cAs'E.

METHOD 0F AND APPARATUS FOR METAL CASTING APPLICATION FILED MAR. 3. 1921.

1,429,568. Patenteasept. 19, 1922.

' 2 SHEETS-SHEET 2.

Patented Sept. 19, 1922.

UNITED STATES ROLLAND T'. CASE, OF LA GROSSE, WISCONSIN.

METHOD OF AND APPARATUS FOR METAL CASTING. v

Application liled March' 3, 1921. Serial No. 449,311.

To all 107mm 'it may concern.'

Be it known that I, ROLLAND T. CASE, a citizen of the UnitedStates, and resident of La Crosse, in the county of La Grosse and State of lVisconsin, have invented new and useful Improvements in Methods of and Apparatus for Metal Casting, of which the following is a description, reference being had to the accompanying drawings,vwhich are a part of this specification.`

This invention relates to improvements in and method of forming centrifugal metal casting, more particularly, although not solely, adapted for dental inlay work.

In inlay casting precious or other metals, a mold is formed around a waX pattern, and when completed, the wax or other Yinvestment is melted and .dischargedl from the mold. The mold is formed withv a tapered mouth leading to the recess in which the casting is made. In ordinary practice, the mold is mounted on a revoluble member, and a Crucible containing the molten metal is also placed on the revoluble member adjacent the mouth of the mold, and upon rapidly revolving the member horizontally or perpendicularly, the molten metal is discharged centrifugally into the mouth of the mold and then into the mold recess where it quickly cools and becomes hard. l/Vhen hard, the mold is broken to remove the casting. As there is comparatively considerable space between the crucible and the mouth of the mold and from the outer portion of the mouth tothe mold recess, the molten metal in passing from the crucible passes through the space and drops on the inclined portion of the mold and climbs up said inclined portion and into the mold recess, and is more or less chilled before it reaches said mold recess with the result that the metal does not completely fill all of the minute crevices of the mold recess and the casting is not as perfect as could be desired. Furthermore, the molten mass; of metal in passing fromthe crucible to the mouth of the mold will splash againstthe mouth portion of the mold and divide into small particles, and these particles will become chilled and partly hard before they enter the mold and form an imperfect castgft isi one of the objects of the present inventionto overcome the before mentioned objectionable features, and provide a means for and method of forming centrifugal castings in which the molten metal is guided and driven into the mold recess in the most direct and efficient manner without permit ting the molten metal to splash or become chilled before it enters the mold recess.

A further object of the invention is to provide a method of and apparatus for forming dental inlay 'castings in which the mold and the Crucible are formed of such shapes as to practically eliminate space between the mold and the crucible and in which the mold is newlyconstructed for each casting and is destroyed to remove the casting.

A further object of the invention is to provide a method of and apparatus for forming dental inlay castings in which a wax pattern may be so positioned on the sprue pin and the sprue pin holder so shaped as to form a mold which will -closely lit the discharge end of thecrucible.

A further object of the invention is to provide a method of and apparatus for forming dental inlay castings in which the operator may easily change the form of the Crucible portion of the apparatus `which holds the molten metal to suit any condition` whichy might arise in casting unusual shapes or rotating the mold in any direction.

A further object ofthe invention is to provide a method of and apparatus for forming dental inlay castings, which is of simple construction, is eflicient in operation and is well adapted for the purpose described.

With the above and other objects in View, the invention consists of the improved method of and apparatus for forming dental inlays,v and its parts and combinations as set forth in the claims and all equivalents thereof.

ln the accompanying drawings in which the same reference characters indicate the same parts in all of the views:

Fig. l is a side view of a centrifugal casting machine showing portions of the improved apparatus used in carrying out the method of casting dental or other inlays;

F ig. 2 is a longitudinal sectional view, on a larger scale, of a portion of the casting machine and the mold and the crucible;

F ig. 3 is a vertical sectional view of the apparatus illustrating one of the steps in carrying out the improved method; and

Fig. 4 is a perspective view of the improved crucible used in the improved 8 indicates a centrifugal dental Casting machine which may be of any of the Well known forms, and either ofthe horizontal revoluble type, as shown, or of the vertical revoluble type. The said machine is adapted to be mounted on a support 9, and com-I prises a vertical shaft 10 having `Aa horizontally extending arm 11 mounted on its upper end portion, which at one end is provided With a mold holder 12 and a Crucible holder 13, andV at its other end a counterweight 14tto counterbalance the Weight of the Crucible l5 and the mold 1G removably Carried by the holders. The opening to the Crucible holder extends inwardly towards the axis of the vertical shaft so that the mold and the Crucible Will be maintained in position and the molten metal be discharged from the Crucible into the mold recess by Centrifugal force. A transversey holden bar 12 Carried by the holder 12 provides for holding molds of less diameter than the holder 12. The vertcial shaft 10 is rotated at comparatively high speed by the manually operated gear connection '17. The balance of the apparatus used in carrying on the steps of the improved method consists of a tubular flask 18 andl a sprue pin holder `and mold former 19. l The flask 18 is preferably of cylindrical form and is open at both ends, and When forming the mold, is adapted to be placed over the conical portion 2O of the sprue pin holder 19. Said conical portion 20at its apex is provided With an upstandingY sprue pin 21 upon the upper end of which the Wax pattern 22 is mounted. The conical portion is also provided with a lip recess former adjacent the apex and a .part annular shouldered portion 2ilcorresponding in diameter to the diameter of the bore of the flask 1S.

ln carrying out the steps of the method, thevvax pattern is made of the tooth cavity or other part, and is mounted upon the pointed end of the sprue pin, and the blunt end of said pin is inserted into the pin recess 25 ofsaid conical portion. rlhe flask tube 18 is now inserted over the conical portion of the sprue pin holder in the manner shown in Fig. 3, and an investment compound or other molding material 26, `While in a plastic condition, is poured into the upper open end of the tube While the lower end of the tube is closed by the sprue pin holder 19. As soon as the investment compound has set or become hard, the tube with the mold is removed and the sprue pin is Withdrawn from the mold. Vifhen these parts are removed, the application of heat to the pattern 22 Will'cause it to melt and flov7 out of the mold recess 27 through he sprue opening 27 formed by the sprue pin 21. As thus formed, the receiving end of the mold will have a conical recess 28 leading to the sprue opening 27, a lip recess 29 below the entrance to said opening, and a part annular recess 30. The crucible 15 which is preferably formed of lire clay, or other like material, is formed With a conical 'end portion 31 having a discharge lip 32 and a part annular shoulder 33 `to closely fit the corresponding` parts of the conical end portion of the mold in the manner shown in Fig. 2.

ln use in casting, the parts are assembled as shown in Fig. 2, and themetal in the crucible is melted by a flame and blow pipe. l.lhen the metal is of 4'the' proper tempera-r ture, the casting machine is rotated to cause 'the molten metal to travel upwardly directly into the mouth or sprue opening and into the mold bycentrifugal force in a most direct path Without loss of heat or metal, and the metal Will completely fill the mold recess While ina fused state, and as cooled by further rotation of the mold. a perfect casting will be made. .lVhen the casting operation is Completed, theinvestment material is broken and removed from the flask member to remove the casting.

From the foregoing description, it will be seen that the'improved method of and apparatusfor casting isyvell adapted forthe purpose described.

VJhat l claim as my invention is:

1. ln combination with a Crucible having a conical discharge spout, of a mold therefor, consisting of a mold member having a molding recess and a conical end recess leading thereto, the portion of the mold forming the conical recess 'being of a shape to closely fit over the conical end portion-of the Crucible to `receive moltenmetal therefrom directly into the moldv recess.

2. Means for forming a mold for a centrifugal casting machine, comprisinga holding member. having an upwardly extending conical portion having a part annular' shoulder, a sprue pin removably'positioned in its upper end for supporting a pattern, anda tubular flask member open at both ends, said flask member extending over the conical portion and engaging the annular shoulder for receiving an investing compound while in a vfluid state to form when vhard a mold having` a conical end recess leading to the mold recess which Willintimately lit one end of a Crucible to be used therewith.

In testimony whereof l affix my signature.

sopraan rJcAsn 

